极限x趋向于无穷大(3x+e^x)^(2/x)

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极限x趋向于无穷大(3x+e^x)^(2/x)
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极限x趋向于无穷大(3x+e^x)^(2/x)
极限x趋向于无穷大(3x+e^x)^(2/x)

极限x趋向于无穷大(3x+e^x)^(2/x)
x→+∞
lim (3x+e^x)^(2/x)
=lim e^ln (3x+e^x)^(2/x)
=e^lim ln (3x+e^x)^(2/x)
考虑
lim ln (3x+e^x)^(2/x)
=lim 2ln(3x+e^x) / x
该极限为∞/∞型,利用L'Hospital法则
=2*lim [ln(3x+e^x)]' / [x]'
=2lim (3+e^x)/(3x+e^x)
=2lim (3+e^x)/(3x+e^x)
=2
因此,原极限=e^2
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